The Ontogeny and Regulation of Corticosteroid Secretion by the Ovine Foetal Adrenal

Abstract

Adrenal glands of foetal sheep of 40 days gestation to term were incubated with and without ACTH or an increased [K+]. With ACTH, the 40 day foetal adrenal was capable of producing more cortisol and aldosterone per g body weight than was the term adrenal. ACTH was a potent stimulus to aldosterone and cortisol production in foetuses aged 60\p=n-\90days, and this effect declined significantly in the 91\p=n-\120day period. An increased [K+] was stimulatory to aldosterone production only after 120 days gestation. Peripheral blood levels of aldosterone, corticosterone, cortisol, 11-deoxycortisol and 11-deoxycorticosterone were measured in foetuses 60 days to term and the levels of aldosterone and cortisol were significantly lower in 90\p=n-\120day foetuses than in the younger or older ones. Direct adrenal vein cannulation proved all five steroids to be secretory products of the foetal adrenal.The ovine foetal cortex has been shown to play a significant role in the onset of parturition in this species (Liggins 1968) and for this reason its ability to

Biochemical modifications involved in the maturation of the ovine fetal adrenal gland in late gestation : their modalities and regulation

“…This results mainly from the growth of the cortical zona and expresses both cellular hyperplasia and hypertrophy (Durand et al, 1978 ;Robinson et al, 1979). The steroidogenic response of fetal adrenal glands to adrenocorticotropic hormone (ACTH) develops simultaneously (Basset and Thorburn, 1973 ;Madill and Basset, 1973 ;Wintour et a/., 1975) and becomes maximal at the time of delivery. In this survey, attention will be focused on results from our laboratories regarding the biochemical steps involved in the enhancement of ovine fetal adrenal cell responsiveness to ACTH between 115 to 120 days of gestation and birth (145 ± 1 day in our experiments).…”

Effects of periconceptional undernutrition on the initiation of parturition in sheep

“…Despite the existence of a functional negative feedback mechanism in the fetal HPAA at 121-131 days gestation, plasma adrenocorticotrophin (ACTH) and cortisol concentrations rise progressively in a semilogarithmic pattern in the last 15-20 days of gestation (14,(32)(33)(34). This sustained release of glucocorticoids is essential for organ maturation and also provides the trigger for the initiation of parturition (7).…”

Aldosterone metabolism in pregnant ewes and fetal and newborn lambs

“…The ability of the adrenal cortex to secrete aldosterone has been the subject of several investigations in fetal lambs (Wintour et al,1975 ;Wintour et al,1977 ;Brown et al,1978) and guinea-pigs (Giry and Delost, 1977) and in human cord plasma at term (Katz, Beck and Makowski,1974 ;Godard, Gaillard and Vallotton, 1976 ; Tochigi Buichi, 1976). However, there are few studies on the metabolism of aldosterone in the pregnant female and the fetus or on the transplacental passage ofthat hormone (Bayard ef al.,1970a, b ;Giry and Delost, 1979 60,90,120,135,150,160 and 180 min after the start of the infusion, and 1 ml of fetal blood was taken at 90, 120, 150 and 180 min 0.80 y c ilmin of [1,2,6,7-3 H] d-aldosterone was also infused intravenously in fetal and newborn lambs for up to 3 hrs.…”